1. Field of the Invention
The present invention relates to an apparatus for fixing a cap on each end surface of a filter element during assembly thereof, which filter element is used as an oil filter or an air filter for an automobile.
2. Description of the Related Art
In general, a disposable type filter element is produced by rolling a predetermined length of a strip of a filter material into a cylindrical form, after the strip has been corrugated, and mounting a cap at each end surface to hold the thus-obtained cylindrical form.
In the prior art, as shown in FIGS. 5a and 5b, an end cap 2 is prepared by applying an adhesive 3, such as polyvinyl chloride from a nozzle 1 onto a disc 2a made of steel and smearing the same uniformly over the inner surface of the disc 2a by a pallet 4. Thereafter, the end cap 2 is fitted on the respective end surface of a roll of filter material 5 to form a filter element 6 (see FIG. 5c). Then the filter element 6 is deposited in a hot air oven 7 (see FIG. 5d) to cure the adhesive 3 and fix the end cap 2a on the end surface of the filter element 6. This process, however, requires a considerable time, for example, 15 min., for curing the adhesive, which means that an oven having an extremely large capacity must be used to ensure an economical productivity of the process.
To eliminate the above drawback, an improved end cap 8 has been prepared, in place of the end cap 2 requiring a curing process, by utilizing a paper disc 8a having one surface coated with a hot-melt adhesive 8b. However, a process for effectively applying this latter end cap to a filter element has not been developed yet.